This invention relates to a starting motor and, more particularly, to a gas powered starting motor.
The invention is particularly applicable to a gas powered motor for relatively small, consumer operated implements powered by two or four cycle internal combustion engines such as walk-behind lawn mowers, chain saws, snowblowers and the like and will be described with particular reference thereto. However, it will be appreciated by those skilled in the art that the invention has broader applications and may be used for starting internal combustion engines of larger horsepower than that disclosed, or for driving power tools such as drills and the like where a source of electrical power may not be available or, if available, is hazardous to use.
The majority of consumer operated, portable implements driven by small two or four cycle internal conbustion engines such as walk-behind lawn mowers, chain saws, etc. are supplied with manual, rope pull starting systems. Not surprisingly, safety statistics have shown that there is a definite need to replace the manual rope pull system with an automatic starting system. At present, there are only two commercially marketed starter systems which may qualify as being "automatic." Each of these systems is afflicted with problems peculiar to the lawn mower and chain saw environment which has prevented widespread use.
The first system is the known spring type starter where a spring is precompressed by a manually operated crank mechanism and the released by a switch. Present spring starter systems require substantial operator effort to fully precompress the spring and do not impart sufficient starting torque or impact to the engine for a sufficient time period to insure a satisfactory starting percentage, especially if the engine is "cold." Furthermore, since the spring must be manually precompressed, the system will not be considered "safe" especially in a chain saw environment, where the operator may be perched in a tree while attempting to wind the spring.
The second starting system is the electric start system, which has earned widescale acceptance in starting large internal combustion engines but has met with limited success in the small internal combustion engine market. An inherent deficiency in the use of an electric start system for a lawn mower and chain saw environment is believed to reside in the fact that, at present, a lightweight battery containing sufficient charge capacity to drive the electric motor has not been developed. Furthermore, assuming the development of such battery, the torque characteristics of the electric motor will require substantial gearing to be used with the motor, all of which (the battery, the motor and the gearing) will result in a prohibitive system cost.